Method of stabilizing fats and oils



Patented I o. n mm 1). arson, or ammo. .mmors; assmnons' r ;.m a comm, "or cmcaeorore. moon-anon or more non or an no m.

i v This invention relates to an improved procass of treating oils and fats, and more particularly a process of stabihzmg oils and fats against rancidity; v

6 The tendency of ordinary animal and vegetable oils and fats to become rancid when exposed to the oxygen of the air, is well known; and the eifect of various substances of a catalytic nature in promoting or retarding such tendency and the velocityof the reaction has been studied by' numerous 1nvestigators.

v The present invention is based upon the discovery that the tendency of oils and fate to become rancid can be retarded by treatment with a carotinoid pigment. We have found that the addition of carotinoid pigment alone retards the onset and course of rancidity; but that this retarding can be considerably augmented by heat treatment.

In carrying out our invention, we add to the oil or fat the naturally occurring pi ments of the carotinoid group and follow the addition by heat treatment. The action of the carotinoid pigment under heat treatment results in a considerable bleaching effect so that the oil or fat after treatment is of a much lighter color than it is after the addition of the carotinoid pigment and before the heat treatment. The carotinoid pigments, being naturally occurring lipochr'omes, color the fat toa yellow or orange shade.

The heat treatment of the oil or fat, following the addition of the 'carotinoid pigment, may be accompanied by hydrogenation, 'or by refining processes involving the addition of alkalies, or by deodorization by means of steam or gases at elevated temperatures. Ordinarily, in the heat treatment the temperature is maintained above the boiling point of water, but below the decomposition temperature of the fat under treatment.

The carotinoid pigment employed in the present process may be that extracted from carrots, alfalfa leaves or other sources; or it may be added to the oil or fat in theform of palm oilor other highly colored fat in which this type of pigment is present in considerable concentration.

' A.ccording to one preferred method of clusion, the invention is not limited to this air-are J one i Ap plioation filed mu a, mac. serial no,

carrying out the invention, there is added to lard, peanut oil, cocoanut oil, cotton seed oil, 1 corn oil, or other oil or fat, about 5% of palm oil, and the mixture is then'heated and l refined and deodorized; or the mixture ma be refined, hydrpgenized and deodorize While 5% to 10% of palm oil is a convenient and sufiicient amount to add in most cases in carrying out-the invention to a practical conamount and may vary over a considerable range, for example, between 1% and 50% or more. The upper limit is determined by the practicability of'applying the refinin rocess' and of producing the light eolore nal product. If the palm oil which is used has a low fatty 'acid content and if there is no objection to a certain amount of color in the final product, a considerablev percenta of palm oil can be used. With a good grad: of palm oil, complete bleaching maybe attained during the course of ordinary deodorizing, or of hydrogenation, or both, even thoggh very large quantities ofpalmoil are use Instead of using palm oil as a source of the carotin, carotin derived from other sources may housed, and added in large or small amounts, depending upon the degree of stability which it isfdesired to ttain. The degree of stability can be deter ined by well known laboratory methods ucb, for example, as holding a sam 1e [under heat at various temperatures an determining the time required for the onset of rancidity; or 85 by determining the oxygen absorption constants of the product; or bydetermining the aldehydes produced at a given temperature during a given time when air or oxygen is bubbled through the oil. For determining stability in bakery goods, the so-called pie crust test may be used, in which a given amount of oil or fat to be usedas shortening is incorporatedin the pie crust and'the length of time required for the onset of rancidity at a given temperature determined. By such tests, the product of the present in: vention has'been found to have a high rating, and to'be a superior shortenin product.

The invention will be further 1 ustrated 1 by the following example, giving a typical illustration of the way in which the invention ma be applied, but it will be understood t at the invention is not limited thereto:

There are introduced into an ordinary refining tank with a capacity of about 60,000 pounds, 57,000 pounds of cocoanut oil, cotton seed oil, oleo oil or lard,.or other oil or fat, and about 3,000 pounds of a good grade of palm oil, preferably containing not more than 10% of free fatty acids, although a higher content of free fatty acid does not interfere with the subsequent processes. A highly colored palm oil containing much carotinoid pigment is desirable. The ingre dients are mtroduced in the liquid form and are thereafter heated in the refining kettles to a suitable refining temperature, usually around 130 to 140 F. An amount of caustic soda proportioned to the free fatty acid content of the mixture is next introduced and the contents of the tank agitated until the soaps are formed and a break obtained, when agitation is stopped and the foots are allowed to settle. After the foots have settled, the supernatant oil is drawn off, clarified by filtering if necessary, with or w thout a clarifying agent such as diatomaccous or fullers earth and then introduced into a steam. .deodorizer, preferably a vacuum deodorizer, where the oils are heated to a suitable deodorizing temperature. for example, around 360 to 420 F., and for a suflicient time to obtain a bland product.

During the heating of the oils or fats, the carotinoid pigments undergo 'a bleaching action and are modified thereby. The refined product, produced according to the above example, is practically free from fatty acids and is colorless or white, or nearly so, in color, although with lower temperatures for deodorizing, products of various shades of yellow may be obtained. The product shows a negative Kreis test and is stabilized against rancidity so that it will keep much better in storage or in bakery products than the untreated oils or fats.

When the product is to be hydrogenated, the hydrogenation step or treatment is carried out after the product is refined and before deodorizing.

We have found that the maximum stabilizing effect of carotinoid pigments appears to be obtained when the product is subjected to hydrogenation with the pigment included. The presence of the pigment itself seems to have some effect on the course of the hydrogen absorption by the fat. apparently acting as a catalyst for hydrogenation. It may be also that the carotinoid pigments are broken down or hydrogenated during'the hydrogenation in such a way that they become more effective as stabilizers or anti-oxidants than when subjected merely to heat treat- 2. The process of stabilizing fats and oils.

against rancidity which comprises adding carotinoid pigment to a fat or oil which is substantially free from free fatty acids, and subjecting the resultant mixture to heat treatment at a temperature suflicient to effect a bleaching of the mixture and the production of a light colored product.

i 3. The process of stabilizing fats and oils against rancidity which comprises adding carotinoid pigment thereto, treatingwith caustic to remove free fatty acids, hydrogenating the refined mixtureto efl'ect bleaching and increased stabilization of the mixture, and d odorizing the same.

4. The process of stabilizing fats and oils against rancidity which comprises aiding thereto about 5 to 10% of palm oil rich in carotinoid pigment, treating the mixture with caustic to remove the free fatty acids, and subjecting thereafter to heat treatment at temperatures between the boiling point of water and the decomposition point of the oil or fat for a sufiicient time to effect a'bl'eaching of .the mixture and the production of a light colored product. I 5. The process of stabilizing fats and oils against rancidity which comprises adding thereto from 5 to 10% of palm oil. treating the mixture with caustic to remove free fatty acids, hvdrogenating the refined mixture to e 'ect ble chin and increased stabilization thereof and deodorizing the mixture.

6. The process of stabilizing lard against rancidity which comprises adding carotinoid pigment thereto. and subiecting the resulting product to heat treatment at temperatures between the boiling point of water and the decomposition temperature of the lard.

In testimony whereof I aflix my signature.

ROY C. NEWTON.

In testimony whereof I afiix my signature.

WILLIAM D. RICHARDSON. 

